It is preferable, and often necessary, to have a means and method for joining products or materials, particularly those manufactured in a continuous process such as weaving, extrusion or rolling, to each other or a second material in a manner which embodies as many of the characteristics of the original product, for example, physical form or chemical properties, as is possible. For example, when joining cylindrical substrates it is frequently advantageous to maintain an unbroken cylindrical form with minimum disturbance of the inside and outside diameters. Similarly, it is often advantageous to join flexible materials with a flexible material or metallic members by means of an intermetallic joint while preserving the basic form or configuration.
Such considerations are particularly significant when the mechanical properties of the joint must be closely matched to those of the substrates. A rigid crimp joint on a soft line can cause the line to be extruded into a thin weak section while a soft joint on a rigid line is prone to being overstressed by the stronger material on either side. Furthermore, the shape or silhouette of the joint can be significant also. For example, a continuous form is less prone to stress points than a discontinuous one. A discontinuous joint may also be undesirable simply becuase it cannot fit into the space demanded of it or be undesirable because an electrical or chemical continuity has been interrupted.
In general it can be said that it is difficult to obtain a union between materials once they have been produced having properties that closely approach the properties of the materials themselves. The joining of metallic substrates exemplifies these problems. For example, as many products are becoming ever smaller in response to the demands of modern technology, arc or gas welding is becoming an increasingly unwieldy, if not impossible, process to employ in diverse applications. Also, the high heat generated in such processes can be a problem if the products to be joined or surrounding materials are delicate.
Conventional soldering is inappropriate where the union formed must have substantially the same inner or outer configuration. Solder must also be contained once melted and if the substrates being joined are large in dimension or mass, the heat required to bring them to the soldering temperature may damage surrounding materials. Furthermore, in conventional soldering the heat and solder are both applied from the outside of the joint to be formed. This is ineffective in joining substrates that are of woven, perforated or otherwise porous construction, because the molten solder will flow longitudinally along and/or through the intersticies of the hot outer substrate, and will not consistently flow into the intersticies of the cooler inner substrate.
The joining of metallic members to each other or a plastic member by means of a fusible plastic adhesive is accompanied by many of the problems encountered in soldering particularly that of containing the melted material to achieve a specific form. Furthermore, pressure is usually required when a plastic bond is made and its application is extremely difficult when it must be applied over a cylinder, sphere or more complex configuration.
Simple compression joints may avoid some of the problems associated with plastic adhesives but are themselves attended by different problems. For example, the high pressure necessary to make a vibration or otherwise stress-resistant joint between the fastener and substrates being joined may damage delicate parts. Also, this pressure tends to embrittle and/or distort or reduce the cross-sectional area of the materials being joined. Mechanical fasteners also tend to be bulky and to require complex machinery for their installation as use of a simple tool may result in overstressing of the joint by the operator. If a sophisticated tool is used, it is usually large in relation to the job and expensive. Furthermore, it does not entirely eliminate the possibility that excessive force will be applied in crimping, tightening or swaging operations.
In view of the problems outlined above faced by those skilled in the art of joining materials, there has gone unsatisfied a long standing need for coupling means and a method by which it is used to effect the union of materials that will substantially preserve the configuration of the substrates and their physical or chemical properties that are physically and economically suitable for both field and factory application under a variety of conditions.
Accordingly, it is an object of the present invention to provide an improved coupling means for joining materials. It is another object of this invention to provide an improved method for joining substrates. More specifically, it is an object of this invention to provide a coupling means and a method by which it is used to form a joint between substrates that substantially preserves their configuration and properties.
The satisfaction of these and other objects by the present invention will be apparent to those skilled in the art after consideration of the following description of the invention.